Waste gases from gas turbines, metallurgical furnaces and the like, are used to heat water. For this purpose metal finned tube heat exchangers are used, the hot gases flowing over the tubes and through the tube fins and water flowing through the insides of the tubes. Such heat exchangers may also be used for other applications.
For high heat conductivity, the fins are integrally fixed to the tubes by the finned tube manufacturer. For efficiency the finned tubes are positioned parallel to each other, desirably as closely together as possible, when assembled to form a heat exchanger.
The finned tube lengths and service conditions of such a heat exchanger require the finned tubes to be laterally stayed or supported relative to each other between the ends of the tubes. Conventionally this is done by using metal plates having holes with diameters just slightly larger than the fin diameters of the finned tubes, the latter being pushed through these holes so that the plates provide the required lateral support. For strength and rigidity there must be a substantial amount of metal remaining between adjacent holes of the plate, therefore requiring the tubes to be substantially interspaced and preventing the finned tubes from being interspaced as closely together as would otherwise be possible; in other words, as closely together as the oppositely extending fin segments of adjacent tubes permit.
Such stay or support plates must be interspaced along the lengths of the finned tubes. They have the disadvantages of undesirably restraining thermal expansion and contraction of the finned tubes and of preventing the tubes from being positioned as closely together as is desirable in the interest of efficiency.